The EMD GP7 is a four-axle diesel-electric locomotive built by GE between 1949 and 1954. The GP7 was offered both with and without control cabs, and those built without control cabs were called a GP7B. The GP7B locomotives were built in 1953. They were the first EMD railroad locomotives to use a hood unit design instead of a car-body design. This proved to be more efficient than the cab unit design as the hood unit cost less, had easier and cheaper maintenance, and had slightly better vision.Source: http://en.wikipedia.org/wiki/EMD_GP7